1. Field of the Invention
The present invention relates to a hybrid vehicle which is equipped with two kinds or more of prime movers for running a vehicle.
2. Related Art
In the prior art, there is a hybrid vehicle which is intended by combining two kinds or more kinds of prime movers to improve an overall efficiency while exploiting the merits of the individual prime movers and compensating the demerits. One example of this hybrid vehicle is disclosed in JP-A-7-186748.
The disclosed hybrid vehicle employs an engine and an electric motor as the prime movers of the two kinds and is constructed such that the drive force of the engine is transmitted to either the front wheels or the rear wheels whereas the drive force of the motor is transmitted to the wheels to which is not transmitted the drive force of the engine.
On the other hand, this hybrid vehicle is equipped with a controller for controlling its running state. To this controller, there are inputted a variety of signals which indicate the running states including the RPM and throttle opening of the engine, the steering angle, the depression of the brake pedal, the depression of the accelerator pedal and the gear position. The controller controls the motor to assist the drive force by the motor at an acceleration or deceleration when the vehicle runs straight or at a small steering angle.
However, what is performed by the hybrid vehicle, as disclosed in the aforementioned Laid-Open publication, is to compensate the shortage of the drive force of the engine with the rotational drive of the motor on the basis of the various signals, as inputted to the controller, at an acceleration or deceleration when the vehicle runs straight or at a small steering angle. In other words, the drive force of the motor is simply used to assist the drive force of the engine, but the control cannot satisfy the specific running state, as intended by the driver. Thus, it cannot be said that the hybrid vehicle sufficiently exploits the motor for improving the running performance and the drivability.